and https://gdal.org/programs/gdaltransform.html
-Matt From: gdal-dev <[email protected]> On Behalf Of Simon Eves Sent: December 10, 2021 12:21 PM To: Yann-Sebastien Tremblay-Johnston <[email protected]> Cc: gdal dev <[email protected]> Subject: Re: [gdal-dev] Transforming Raster Points from GeoTIFF with GCPs *** External email: Do not click on links or attachments except from trusted senders. *** ****************************************************************************************** Aha! That's the bit I hadn't found. Thank you! :) On Fri, Dec 10, 2021 at 10:38 AM Yann-Sebastien Tremblay-Johnston <[email protected]<mailto:[email protected]>> wrote: Simon, See the Transformer API, in particular https://gdal.org/api/gdal_alg.html?highlight=transformer#_CPPv419GDALTransformerFunc (or gdal.Transformer in Python). Sebastien On Fri, Dec 10, 2021 at 10:24 AM Simon Eves <[email protected]<mailto:[email protected]>> wrote: So we have a GeoTiFF of Sentinel-1 imagery which `gdalinfo` reports as having a GCP projection with 210 points, which we'd (perhaps naively?!) like to import directly, transforming to WGS84 on the fly. Obviously a simple OGRSpatialReference/OGRCoordinateTransformation transform isn't going to do anything, so I assume we have to do the GCP transform manually. I found the GCPCoordinateTransformation class and other supporting code in ogr2ogr_lib.cpp as used by gdaltransform, which seems to do what we need, but of course it's not in the core GDAL library so we can't "just use it". Before embarking on lifting out that code to implement an on-the-fly transformer in our system, I just wanted to make sure I wasn't missing any functionality elsewhere that would make it easier. It may also be more efficient to just kick off a gdalwarp to pre-convert the file so we can just import it with no transformation required, but that seems ugly unless it's gonna be WAY more efficient? Thanks, Simon -- [http://www2.omnisci.com/l/298412/2018-09-18/3sqpg/298412/61753/OmniSci_Email_Header2.png]<http://www.omnisci.com/> Simon Eves Senior Graphics Engineer, Rendering Group 100 Montgomery St (5th Floor), San Francisco, CA 94104, USA Email: [email protected]<mailto:[email protected]> | Cell: +1 (415) 902-1996 _______________________________________________ gdal-dev mailing list [email protected]<mailto:[email protected]> https://lists.osgeo.org/mailman/listinfo/gdal-dev -- [http://www2.omnisci.com/l/298412/2018-09-18/3sqpg/298412/61753/OmniSci_Email_Header2.png]<http://www.omnisci.com/> Simon Eves Senior Graphics Engineer, Rendering Group 100 Montgomery St (5th Floor), San Francisco, CA 94104, USA Email: [email protected]<mailto:[email protected]> | Cell: +1 (415) 902-1996
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